This invention relates to the detection of mail and in particular to detection that a mail item is correctly positioned to receive a postage imprint.
Postal authorities require that postal indicia are printed in a specified position in the upper right hand corner of mail items. Accordingly, in printing devices for printing postal indicia on mail items, it is necessary that the mail item be correctly positioned relative to a print head to ensure that the postal indicia is printed in the specified position on the mail item. In postage meter printing devices in which the mail item is fed along a feed bed by a mail transport mechanism, the mail item is inserted with an upper edge thereof in engagement with a guide and the transport mechanism then feeds the mail item while maintaining the upper edge of the item in engagement with the guide. When a leading edge of the mail item is sensed by a sensor, printing of the postal indicia is initiated. The position of the guide relative to the print head determines the spacing of the printed indicium from the upper edge of the mail item and the position of the sensor determines the spacing of the indicium from the leading right hand edge of the mail item. Thus it will be appreciated that the sensor is required only to detect movement of the mail in one direction, namely the direction in which the mail item is fed by the transport mechanism.
In postage metering apparatus intended to handle a smaller number of mail items, the mail item transport mechanism is dispensed with and the mail item is inserted into the apparatus and must be correctly positioned manually. Accordingly it is necessary to provide mail detection means capable of ensuring that the mail is correctly positioned is mutually perpendicular directions prior to initiation of printing of the postal indicium.